HOW ARE THE PROPERTIES OF INFANT FORMULAS AFFECTED BY THE PROTEIN SOURCE USED?

Infant formulas are products used to replace or supplement breast milk. Most of them contain cow's milk as the main raw material and protein source, nevertheless, soy protein isolates may also be used as a protein source to replace milk. Due to the high nutritional and economic value of such products, it is essential to evaluate how the different protein sources may impact on the infant formula properties. For this purpose, infant formula based on cow's milk and soy proteins were purchased from the local market, and compared in terms of moisture content (gravimetric method), sorption isotherm (DDI method), solubility index (determination of solids after centrifugation), browning index (colorimeter), advanced glycation products content (AGEs - fluorescence), antioxidant capacity (ABTS and ORAC) and electrophoresis (SDS-PAGE). Among the evaluated parameters, only moisture content did not vary between samples. The sorption isotherms displayed different profiles with a characteristic lactose crystallization inflection point for the formula containing cow's milk. Such inflection point was absent in formula containing soy proteins since it has no lactose-added. The formula containing soy proteins were significantly more soluble than the formula containing cow's milk. This same behavior was observed concerning the browning index and fluorescence of AGEs. The antioxidant capacity of formula containing soy proteins was significantly higher in both methods than formula containing cow's milk, probably due to the presence of phenolic compounds from the plant matrix. As expected, the electrophoretic profile differs significantly between the two formulas. Therefore, the infant formulas evaluated displayed differences for almost all evaluated parameters, indicating that the protein source substantially influences the properties of such a product. Moreover, such results are relevant in establishing parallels between different infant formulas that aim to meet the same nutritional demands of infants.